Income Taxes (Details 2) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Tax carryforwards [Abstract]
Deferred Tax Assets, Tax Credit Carryforwards, Foreign	$ 3,798
Assets
Other current assets	0	$ 29
Other noncurrent assets	1,222	525
Liabilities
Other current liabilities	0	3
Noncurrent deferred tax liabilities	2,441	2,486
Deferred Tax Liabilities, Net	1,219	1,935
Libya [Member]
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets, Operating Loss Carryforwards	84
UNITED STATES
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets, Operating Loss Carryforwards	365
State and Local Jurisdiction [Member]
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets, Operating Loss Carryforwards	1,415
EQUATORIAL GUINEA
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets, Operating Loss Carryforwards	81
Foreign Country Kurdistan [Member]
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets, Operating Loss Carryforwards	208
CANADA
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets, Operating Loss Carryforwards	863
Foreign Tax Authority [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Valuation Allowances and Reserves, Adjustments	54	41	$ (61)
Internal Revenue Service (IRS) [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Valuation Allowances and Reserves, Charged to Cost and Expense	$ 45		$ 930
Impairments and Exploration Expenses [Abstract]
Valuation Allowance Deferred Tax Asset Change In Amount Foreign		$ 222